Removed an if statement that was causing addHydrogens() to fail for systems containing OH groups.

wrappers/python/simtk/openmm/app/modeller.py

@@ -734,9 +734,8 @@ class Modeller(object):
                                     else:
                                         delta = Vec3(random.random(), random.random(), random.random())*nanometer
                                     delta *= 0.1*nanometer/norm(delta)
-                                    if len(expected) > 1:
-                                        delta += 0.05*Vec3(random.random(), random.random(), random.random())*nanometer
-                                        delta *= 0.1*nanometer/norm(delta)
+                                    delta += 0.05*Vec3(random.random(), random.random(), random.random())*nanometer
+                                    delta *= 0.1*nanometer/norm(delta)
                                     newPositions.append(self.positions[parent.index]+delta)
                                     newTopology.addBond(newAtom, newH)
                 else:
@@ -922,4 +921,4 @@ class Modeller(object):
             if bond[0] in newAtoms and bond[1] in newAtoms:
                 newTopology.addBond(newAtoms[bond[0]], newAtoms[bond[1]])
         self.topology = newTopology
-        self.positions = newPositions
+        self.positions = newPositions
\ No newline at end of file